Numerous experiments have confirmed that if the distance between a light source and an observer is doubled, the intensity of the light as viewed by the observer decreases by a factor of four. Which type of scientific statement is this?
Correct Answer: A
Explanation:
The statement that if the distance between a light source and an observer is doubled, the intensity of the light decreases by a factor of four, describes a consistent, repeatable observation that has been confirmed through numerous experiments. This describes a scientific law, specifically the inverse square law of light. A law summarizes a pattern found in nature, whereas a hypothesis is an untested prediction, a theory is a well-substantiated explanation, and an inference is a conclusion drawn from evidence. Reference: Integrated Physical Sciences, Chapter 4: Scientific Laws and Theories
Question 2
Which question would be appropriate for an observational study?
Correct Answer: D
Explanation:
An appropriate question for an observational study is one that involves collecting data through observation without manipulation. "What types of rocks are found at a convergent boundary?" requires observing and identifying the types of rocks naturally occurring at such geological formations. It doesn't involve changing any variables, fitting the definition of an observational study. Reference: Integrated Physical Sciences, Chapter 2: Methods of Scientific Investigation
Question 3
A scientist wants to determine how the speed of flowing water affects the size of sediment particles it can carry. The scientist places a mix of sediment particles in the bottom of a trough and runs water through the trough. The scientist varies the speed of the water and measures the sizes of the particles that the water carries away. Which type of investigation is the scientist using?
Correct Answer: B
Explanation:
The scientist is determining how the speed of flowing water affects the size of sediment particles it can carry by varying the water speed and measuring the sediment sizes. This involves manipulating one variable (water speed) and observing the effect on another variable (sediment size), which is the essence of a controlled experiment. The setting and control of conditions ensure that the experimenter can establish a cause-and-effect relationship.
Reference: Integrated Physical Sciences, Chapter 2: Methods of Scientific Investigation
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